The present disclosure relates to a semiconductor structure, and more particularly to a semiconductor-fin-on-oxide structure providing reduced leakage current, and a method of manufacturing the same.
Semiconductor-fin-on-insulator structures refer to a structure in which at least one portion of a semiconductor fin is vertically spaced from an underlying semiconductor material layer by an insulator layer. A fin field effect transistor employing a semiconductor-fin-on-insulator structure can have enhanced electrical isolation between the channel region and the underlying semiconductor material layer compared with a fin field effect transistor that does not employ an insulating layer between the channel and the underlying semiconductor material layer.
Despite the enhanced electrical isolation of the channel from the underlying semiconductor material layer, fin field effect transistors employing a semiconductor-fin-on-insulator structure suffer from drain-induced fringing field originating from the bottom of a drain sidewall, extending through the insulator layer, and terminating on the bottom of the channel, which results in a parasitic leakage path. Further, the source-to-drain distance at the bottom of the source region and the drain region below the portion of the insulator layer underneath the channel is the same as the channel length. This feature results in a significant source-to-drain leakage current underneath the channel through the underlying semiconductor material layer where the effect of the electrical field applied by the voltage at the gate electrode is insignificant. The source-drain leakage current underneath the channel necessitates formation of a punchthrough stopper region having a high concentration of electrical dopants.